[noun] + の間に
[noun A] + と + [noun B] + の間に
The grammar structure の間に is used to express that something happens during or while a certain period or event is taking place. It attaches to nouns to indicate the time frame within which an action occurs.
When attached to a noun representing a time period or event, の間に indicates that something happens at some point within that period.
の間に can also express "between" two things – whether physical locations or abstract concepts. In this case, the structure is A と B の間に.
An important distinction exists between の間に and の間 (without に).
の間に – Something happens at a point within the time frame. The action in the main clause is typically a one-time or completed event.
の間 – Something continues throughout the entire time frame. The action in the main clause is ongoing or sustained.
The particle に highlights that the event occurred within the period rather than spanning it.
While の間に is used with nouns, the same concept applies with verbs using V[ている] + 間に or V[dictionary form] + 間に. These are closely related patterns worth knowing.